1. Field of the Invention
The invention relates to a circuit arrangement for operating a semiconductor light source provided with:
connection terminals for connection to a control unit,
input filter means,
a converter comprising a control circuit, and
output terminals for connection to the semiconductor light source. The invention also relates to a signalling light provided with such a circuit arrangement.
2. Description of the Related Art
Semiconductor light sources are increasingly used as signalling lights. A semiconductor light source in such an application has the advantage over a usual incandescent lamp that it has a longer life and a considerably lower power consumption than the incandescent lamp. Signalling lights often form part of a complicated signalling system, for example, a traffic control system with traffic lights. It is necessary for the circuit arrangement to provide retrofit possibilities in respect of existing signalling systems if the above advantages of semiconductor light sources are to be realized on a wide scale.
A signalling light in an existing signalling system is often controlled by means of a control unit which includes a solid state relay, a status test of the relay and of the signalling light taking place at the connection terminals of the connected circuit arrangement. It is a general property of solid state relays that a leakage current occurs in the non-conducting state of the relay. The use of a semiconductor light source is apt to give rise to an incorrect outcome of the status test. This is a problem in the use of the semiconductor light source.